The electroreduction of CO2 to methanol by hydrogenation is one of the important methods to decrease the green house effect induced by CO2 and to renew fuels. The catalytic properties of CuZr nanoparticles on CO2 hydrogenation to methanol were researched by using the Density Functional theory calculation. The adsorption energies for the reactants, intermediates, and products, the energy barrier and reaction energy at each elementary step via 'RWGS+CO-hydro’ pathway, were calculated. It is found that all the adsorption and reaction processes are performed around Zr atom, and the catalytic activation of CuZr nanoparticles is not only related to their size, but also to Zr atom doping site. That is to say, the size role on the adsorption energies is usually larger than the role of Zr atom doping site. Zr atom doping site has greater contribution to the energy barriers, especially at the rate determining step. According to the obtained results, the relation between the catalysts’ structure and the catalytic activation for CO2 conversion to methanol was further supported.